johanson



T. -A. JOHANSON.

PIANO souuomo BOARD AND FRAME.

Patented Nov. 23, 1920.

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T. A. JOHANSON.

PIANO souuoma BOARD AND FRAME.

APPLICATION FILED SEPT. 23, H8.

Patented Nov. 23, 1920.

1 2W, 0. my

KZ M.

UNITED STATES PATENT OFFICE.

THURE A. JOHANSON, OF ST. CHARLES, ILLINOIS, ASSIGNOR TO THE CABLE COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

PIANO SOUNDING-BOARD AND FRAME.

Specification of Letters Patent. f t 23, 1920,

Application filed September 23,1918. Serial No. 255,262.

useful Improvements in Piano Sounding Boards and Frames, of which the following is a full, clear, concise, and exact descrip tion, reference being had to the accompanying drawing, forming a part of this specification.

My invention relates to piano soundingboards and frames.

()ne of the objects of my invention is to provide an improved construction for maintaining the proper crown or curvature of piano sounding -boards. Further objects will appear from the detailed description to follow and from the appended claims.

In the accompanying drawings, in which several embodiments of my invention are shown,-

Figure .1. is a bottom view of a grand piano sounding-board and frame construction embodying my invention;

Fig. v2 is a similar view, illustrating another form of my invention;

Fig. 3 is a similar view, illustrating still another form of my invention;

Fig. 4 is a vertical fore-and-aft section,

substantially on the line 44 of Fig. 1;

Fig. 5 is a fragmentary horizontal sectional View, showin the construction of one of the joints of ig. 1;

Fig. 6 is a fragmentary horizontal sectional View, showing, in detail, another joint of the construction of Fig. 1;

F ig. 7 is a fragmentary horizontal sectional view, showing, in detail, a joint of the construction shown in Fig. 2; and

Fig. 8 is a fragmentar horizontal sectional view, showing a etail of another joint of the construction shown in Fig. 2.

In order to give a general idea of the embodiments of my invention illustrated, it is here stated that I have shown it in connec tion with a grand piano in which portions of the edge of the sounding-board are secured to curved portions of theframe of the piano, and a curved bracing-member, forming part of the frame, 13 provided to assist in holding the frame in its proper position. Referring now to the drawings in detail,

a d fir t to the construction shown in Figs.

1, L, 5, and 6, the construction shown comprises the iiranielt of a grand piano, a sounding-board 11, having portions of its edge secured to portions oi the frame 10, a string-plate 12, on which the bass strings 13 and treble strings 14-. are stretched, and the bridges 15 and 1G for the bass and treble strings, respectively.

The bridges 15 and 16 are located between the strings and the sounding-board, the strings bearing on the bridges and the bridges, in turn, bearing on the soundingboard. As the strings on the string-plate are under considerable tension, they bear down with. considerable force on the bridges and this force is transmitted to the sounding-board, the combined effect of all the strings causing a considerable downward pressure to be exerted on the soundingboard, which tends to crush down the crown or curvature thereof and to distort the frame 10 to which the corresponding portions of the edge of the souuding-board are secured. An increase in humidity often causes the sounding-board to swell, which, in turn, tends to increase the crown or curvature of the board. against the pressure of the tion of the frame but nevertheless. giving it sufficiently strong support. This curved bracing-member, in the form shown in Fig. 1, is a semi-cylindrical wooden brace, the ends 18 and 19 of whichare securely fastened to opposite sides of the frame 10 by means of bolts 20'and 21, respectively (Figs. 5 and 6). I

The tension in this curved brace 17 is such that, as it is sprung outwardly when it is secured to the opposite sides of the frame 10, it exerts a force tending-to draw the two opposite sidesof t e frame together.

The middle portion of the brace 1'7 bears against a cross-piece 22, forming part of the frame 10. the ends of which cross-piece are secured to opposite sides of the frame 10.

The pin-block 23 (in which the tuningpins are mounted) is secured to the front edge of the string-plate 12. The forward part of the string-plate is provided with a lug or projection 24:, which bears on a crosspiece 25. also forming part of the frame 10 and extending from one side to the other thereof and secured thereto. The front edge of the soundiiw-board is secured to a liningstrip 26 which. in turn, is secured to the cross-piece so that any pressure of the lug or projection 21 on the cross-piece 25 is transmitted indirectly to the sounding-board and assists in maintaining the crown or curvature thereof.

Adjustable means 26% are provided for transmitting pressure from the lug 21 to the cross-piece 25, these adjustable means. as shown, comprising an internally threaded bearing-member 2? (bearing on the crosspiece 25 and on the lining-strip 26) and a capstan-screw 2S threaded into the bearingmember 27 and having its end in engagement with the lug2-1. By adjusting the capstan-screw 28, the pressure of the lug 2-1 on the cross-piece 25 may be varied.

The soimding-board itself comprises an upwardly bowed diaphragm 29 which is braced and strengthened by ribs 30, secured to the diaphragm 29, this being a usual construction of sounding-board. The stringplate 12 and the sounding-board 11 are secured to the frame 10 by means of screws extending through registering openings in the string-plate 12 and sounding-board 11 into the frame 10. The diaphragm 2-9 is of wood, the grain of which extends transversely with respect to the ribs 30.

The curved brace 17 resists the tendency of the sounding-board to break down under the pressure of the bridges 15 and 16, and also resists the swelling of the soundingboard due to increases in humidity, but this resistance is elastic and some slight expansion of the souinling-board under abnormal pressures. such as occur during humid weather conditions, will be permitted; however, the elasticity of the brace 17 will effect a constant effort to compress the soundingboard cdgewise and to maintain the proper crown or curvature, notwithstanding atmospheric changes. The action of the lug 24: on the sounding-board also tends to prevent its being crushed down under the pressure of the bridges 15 and 16, as the pressure transmitted to the edge of the soundingboard from the lug 24 is such as to tend to hold the sounding-board in its upwardly bowed position.

This construction provides unusual rigidity and is, I believe, preferable to the usual,

heavily braced frame for many reasons, among which are lightness, strength, increased resonance, and improvement of tone, the two latter being, to some extent a resultof the drum-like construction formed by the use of the semi-cylindrical brace in conjunction with the semi-cylindrical portion of the piano frame.

The construction shown in Fig. 2 is substantially the same as that shown in Fig. 1, with the exception of the curved bracingmember and its connection with the sides of the frame. In the construction shown in Fig. 2. an, adjustable. stay 31 is provided for cooperation with the curved bracing-member 32. the stay having its ends secured to the sides of the frame and serving also to secure the ends 34; of the curved bracingmember to the sides of the frame, as indicated in Figs. 7 and 8. The threaded ends 555, 2-36 of the stay extend through registering openings in the curved bracing-member 32 and frame 10, and nuts 37 are screwed onto these threaded ends to hold the parts securely in position. The stay is adjusted in the usual manner by means of a turnbuchlc member 38, with which the ends 35 and 3(3 of the stay have a threaded engagement, the threads being right and left hand, respectively, so that turning the turn-buckle 38 in one direction will draw the ends and 36 toward each other.

in the form of my invention shown in Fig. 3. the construction is substantially the same as in Fig. 1, except that, in the form shown in Fig. 3, the curved bracing-member S5) continued so as to form acomplete cylinder. The portion it) of the bracingmember 39 which lies adjacent the outer frame-portion 4.1 may be secured thereto in any suitable manner, as by gluing, as may be also the inner frame-portions -12 and 43.

In all of the forms, the curved bracingmember may be made up of laminatious of wood glued together.

The combination of the sounding-board 11 with the semi-cylindrical portion of the frame 10 and the semi-cylindrical bracingmember gives a resonant, drumlike construction.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A piano construction comprising a frame having a substantially semi-cylindrical rear portion, portions extending forwardly from said semi-cylindrical rear portion along the sides of the piano, and a curved bracing-member connected to said semi-cylindrical rear portion and forming in combination therewith a substantially continuous cylinder.

A piano construction comprising a frame having a substantially semi-cylindri cal rear portion, portions extending forwardly from said semi-cylindrical rear portion along'the sides of the piano, and a curved bracing-member connected to said semi-cylindrical rear portion and forming in combination therewith substantially a continuous cylinder; and a sounding-board secured to said frame.

3. A piano construction comprising a frame having a substantially semi-cylindrical rear portion, portions extending forwardly from said semi-cylindrical rear portion along the sides of the piano, a ortion forming a curved bracing-member cooperating with said rear portion to form a substantially continuous cylinder, and a cross-piece extending between said forwardly extending portions and secured thereto: the curved bracing-member bearing on said cross-piece.

4. A piano construction comprising a frame having a substantially semi-cylindrical rear portion, portions extending for- I 4 wardly from said semi-cylindrical rear portion along the sides of the piano, and a curved bracing-member connected to said semi-cylindrical rear portion and forming in combination therewith substantially a cylinder; and a sounding-board secured to said frame; the tension in said curved bracingmember being such as to tend to contract said semi-cylindrical frame-portion. I

5. A piano construction comprising a frame having a substantially semi-cylindrical rear portion, portions extending forwardly from said semi-cylindrical rear portion along the sides of the piano, a crosspiece extending between said forwardly extending portions and secured thereto, and

v a curved bracing-member having a semicylindrical portion forming, with said semicylindrical rear portion, substantially a cylinder, the semi-cylindrical portion of said bracinganember bearing on said cross-piece; and a sounding-board secured to said frame.

6. A piano construction comprising a frame having a substantially semicylindrical portion, two portions extending forwardly from said semi-cylindrical portion along the sides of the piano, a cross-piece extending between said forwardly extending portions and secured thereto, and a curved bracing-member having a substantially semicylindrical portion forming, with said semicylindrical frameportion, substantially a cylinder, the semi-cylindrical portion of said bracing-member bearing on said cross-piece; and a string-plate secured to said frame and bearing on said cross-piece.

7. A piano construction comprising a frame having a substantially semi-cylindrical rear portion, two portions extending forwardly from said semi-cylindrical rear portion along the sides of the piano, a crosspiece extending between said forwardly extending portions and secured thereto, and

a curved bracing-member secured to said frame and havinga substantially semi-cylindrical portion forming, with said semi-cylindrical rear portion, substantially a continuous cylinder, the semi-cylindrical portion of said bracing-member bearing on said -ross-piece; a sounding-board secured to said frame and a string-plate also secured to said.

frame and bearing on said cross-piece.

8. A piano construction comprising a frame having a substant ally semi-cylindrical rear portion, two portions extending forwardly from said semi-cylindrical rear portion along the sides of the piano, and a curved bracing-member having a semi-cylindrical portion forming, with said semi-cylin drical rear portion, substantially a cylinder;

and a member extending between the ends ofthe semi-cylindrical portion of said bracing-member.

9. A piano construction comprising a frame having a substantially semi-cylindri' cal rear portion, two portions extending forwardly from said semi-cylindrical rear portion along the sides of the piano, a cross-piece extending between said forwardly extending portions and secured thereto, and a curved bracing-member having a substantially semi-cylindrical portion forming, with said semi-cylindrical rear portion, substantially a cylinder, the semicylindrical portion of said bracing-member bearing ontsaid'cross-piece; and a member extending between the ends of the semicylindrical portion of said bracing-member.

'10. A piano construction comprising a frame having a substantially semi-cylindrical rear portion, two portions extending forwardly from said semi-cylindrical rear portion along the sides of the piano, and a bracing member, comprising a substantially continuous cylinder having a portion thereof extending alongside of and'secured to said semi-cylindrical rear portion.

11. A piano construction comprising a frame havin a substantially semi-cylindrical rear portion, two'portions extending forwardly from said semi-cylindrical rear portion along the sides of the piano, a crosspiece extending between said forwardly 13. A sounding-board, a support or supports for two edge-parts of said soundingboard, and contractile means acting, in a plane substantially parallel with the plane of said sounding-board upon said support or supports to dra i and hold the two edgeparts of said sounding-board in a desired relative position.

ll. A sounding-board, a support or supports for two edge-parts of said soundingboard, and yieldable means extending between. and acting, in a plane substantially parallel with the plane of said sounding board, upon said support or supports to draw and hold the two edge-parts of said sounding-board in a desired relative position.

15. A piano frame, a sounding-board, and yieldable means acting upon said frame, in a plane substantially parallel with the plane of said sounding-board, to cause said frame to impel said sounding-board and yieldingly hold said sounding-board in a desired position.

16. A piano frame having a yieldable tension-member acting between and upon two approximately opposite parts of said frame to impel and yieldingly draw said parts toward each other.

17. A piano frame having a yieldable tensionn1ember acting between and upon two approximately opposite parts of said frame to impel and yieldingly hold said parts in a desired relative position.

18. A piano having asounding-board, and means positioned partially within the area covered by said sounding-board and acting, in a plane substantially parallel with the plane of said sounding-board to resiliently oppose lateral movement of an edge-part of said sounding-b0ard.

19. A piano frame, a sounding-board hav ing an edge-part thereof secured to a part of said frame. and yieldable means acting, in a plane substantially parallel with the plane of said sounding-board, upon said part of said frame to impel and yieldingly hold said part of said frame and said edgepart of said sounding-board in a desired position.

20. A piano frame, a sounding-board having portions of its edge-pant secured to parts of said frame, and yieldable means acting, in a plane substantially parallel with the )lane of said sounding-board, between and upon two of said parts of said frame to impel and yieldingly hold said parts of said frame and said portions of the edge-part of said sounding-board in desired relative positions.

21. A piano including a piano-frame, comprising a hollow drum-like portion having an approximately circular cylindrical exterior, a sounding-board extending across said drum-like portion, a string-plate and strings extending across said soundingboard, and a bridge between said strings and sounding-board.

In witness whereof I have hereunto subscribed my name.

THURE A, JOHANSON. lVitnesses J. CLARK-E HAGEY, Janus M. Nissan. 

